1. Field of the Invention
The present invention relates to a liquid electrophotographic printer, and more particularly, to a development roller cleaning apparatus for removing an excess developer liquid and/or foreign particles remaining on the surface of a development roller which supplies a developer liquid to a photoreceptor medium.
2. Description of the Related Art
In an electrophotographic printer, an electrostatic latent image formed on a photoreceptor medium, such as a photoreceptor drum or a photoreceptor belt, is developed by using a developer liquid comprising a toner and a volatile carrier liquid. The developed image is then transferred to a sheet, thereby printing a desired image.
Referring to FIG. 1, a conventional liquid electrophotographic color printer includes a photoreceptor belt 110 supported by a plurality of rollers 121, 122 and 123 for circulating travel. As the photoreceptor belt 110 travels, a charging station 150 charges the surface of the photoreceptor belt 110 to a predetermined level. Then, a laser scanning unit 130 directs a laser beam onto the photoreceptor belt 110 according to image signals to form an electrostatic latent image thereon. Finally, a development station 140 supplies a developer liquid to develop the electrostatic latent image. As shown in FIG. 1, the color printer has a plurality of laser scanning units 130 and a plurality of development stations 140 corresponding to various colors.
With reference to FIG. 2, each of the development stations 140 includes a development roller 141, a cleaning roller 142 and squeegee rollers 144 and 146 positioned directly under the photoreceptor belt 110. Each development station accommodates a developer liquid 148 including a toner of a predetermined color mixed with a carrier liquid. A developer liquid supplier 143 provides the developer liquid 148 between the development roller 141 and the photoreceptor belt 110.
The squeegee rollers 144 and 146 remove the excess developer liquid from the photoreceptor belt 110. The removed developer liquid is recovered into the development station 140 via blades 145 and 147.
An image drying station 160 dries the carrier liquid of the developer liquid 148 adsorbed onto the electrostatic latent image of the photoreceptor belt 110. Thus, only the dried toner remains on the photoreceptor belt 110.
Subsequently, when the photoreceptor belt 110 passes between the roller 121 (FIG. 1) and the transfer roller 124, the developed image is transferred to a sheet 126, which is fed between the transfer roller 124 and a fixation roller 125. Thereafter, an erasure station 170 removes any electrostatic charge remaining on the photoreceptor belt 110.
Turning to FIG. 3, the cleaning roller 142 has a plurality of orifices for removing the developer liquid that fails to adsorb to the photoreceptor belt 110 and continues around the development roller 141. The orifices 142a penetrate the cleaning roller 142 from its center to its peripheral surface. Therefore, as the cleaning roller 142 rotates in contact with the development roller, the developer liquid 148' remaining on the development roller 141 travels through the orifices and collects in the bottom of the development station.
However, since the cleaning roller 142 requires a driver (not shown) and a developer liquid delivery device (not shown), the structure is complex. Also, fabricating the orifices is difficult. Finally, the friction between the oppositely rotating development roller 141 and cleaning roller 142 causes abrasions that shorten the life span thereof.